Repeat spacing mechanism for typewriters

ABSTRACT

A repeat spacing mechanism for a manual typewriter includes feed and keep pawls that are rotatable in a horizontal plane in conjunction with a horizontal escapement wheel operatively connected to a carriage. A spring is interposed between the feed pawl and a repeat spacing key, wherein the keep and feed pawls are alternately engaged with the escapement wheel and disengaged therefrom so as to cause the carriage to make a repeat spacing movement under control of the bias of the spring while the repeat spacing key is depressed. The spring may be provided with a holding member that is adjustably connected to a lever which is connected to and actuated by said repeat spacing key. In addition, an inertia increasing member may be secured to an end of one of said pawls.

United States Patent [191 Watanabe 1 REPEAT SPACING MECHANISM FOR TYPEWRITERS [75] Inventor: Tomoyoshi Watanabe, Hekikai-gun,

Aichi-ken, Japan [73] Assignee: Brother Kogyo Kabushiki Kaisha,

1 Nagoya-shi, Japan [22] Filed: Aug. 4, 1970 [21] Appl. No.: 60,911

[30] Foreign Application Priority Data [451 May 29,1973

Primary Examiner-Ernest T. Wright, Jr. Attorney-Kemon, Palmer & Estabrook [5 7] ABSTRACT A repeat spacing mechanism for a manual typewriter includes feed and keep pawls that are rotatable in a horizontal plane in conjunction with a horizontal escapement wheel operatively connected to a carriage. A spring is interposed between the feed pawl and a repeat spacing key, wherein the keep and feed pawls are alternately engaged with the escapement wheel and disengaged therefrom so as to cause the carriage to make a repeat spacing movement under control of the bias of the spring while the repeat spacing key is depressed. The spring may be provided with a holding member that is adjustably connected to a lever which is connected to and actuated by said repeat spacing key. In addition, an inertia increasing member may be secured to an end of one of said pawls.

1 Claim, 8 Drawing Figures PATENTEU MAY 2 9 I975 SHEET 2 0F 3 INVENI'OR.

moyasm warn BY PATENTEUHAYZQIQIS sumaur3 7 x mim REPEAT SPACING MECHANISM FOR TYPEWRITERS BACKGROUND OF INVENTION The present invention relates to the repeat spacing mechanism of a manual typewriter or a similar one and more particularly to a spacing mechanism which permits the carriage of such typewriter to make an automatic and continuous repeat spacing movement.

In the operation of a manual typewriter, or a similar one, for example, an electric typewriter, or a so-called semi-electric typewriter involving a non-power driven or manual repeat spacing mechanism there are occasions where it is desired to resume printing by skipping the carriage from a given printing position by several letter spaces. Such spacing has heretofore been effected by presetting the following printing position through operation of a tabulator, by actuating a carriage release lever mounted on the carriage or by repeatedly depressing the space bar.

The first process offers convenience when printing is made in a column having a fixed size as in tabulation. Where, however, it is desired to skip the carriage from one given printing position to another, there has to be repeated the setting and clearing of a tabulator stop, which is undesirably troublesome. With the second process, the typist must remove his hands each time from the keyboard for the desired movement of the carriage, resulting in the derangement of typing rhythm and loss of time. Thus the third process is generally followed. While, in this case, it is unnecessary to take off the hands from the keyboard, there is the trouble of depressing the space bar repeatedly until the carriage is brought to the following printing position.

Where, therefore, there is required the aforesaid spacing operation, there has been demanded such type of manual typewriter or semi-electric typewriter involving a non-power driven repeat spacing mechanism as comprises a repeat spacing mechanism capable of performing the same action as the repeat depression of the space bar merely by a single depression of a particular key.

SUMMARY OF THE INVENTION The present invention has been accomplished in view of the aforesaid situation. The first object of the invention is to provide a compact repeat spacing mechanism of simple construction for manual typewriters or semielectric typewriters involving a non-power driven repeat spacing mechanism.

The second object of the invention is to provide a repeat spacing mechanism for manual typewriters or sembelectric typewriters which comprises a member additionally fitted to the arrangement associated with the first object, thereby allowing the carriage to make a repeat spacing movement at a proper speed.

Other objects, features and advantages of the invention will appear as a detailed description thereof proceeds in the light of the drawing forming a part of this application.

BRIEF DESCRIPTION OF THE DRAWING The present invention can be more fully understood from the following detailed description when taken in connection with reference to the accompanying drawing, in which:

FIG. 1 is a bottom plan view of a repeat spacing mechanism according to an embodiment of the present invention;

FIGS. 2 and 3 are sectional views along lines II--II and IIIIII of FIG. 1 with said FIGS. 2 and 3 rotated clockwise;

FIGS. 4 to 6 illustrate the function of said embodiment; and

FIGS. 7 and 8 are bottom plan views of other embodiments of the invention.

DETAILED DESCRIPTION OF THE INVENTION There will now be described by reference to FIGS. 1 to 6 an embodiment of the present invention. Numeral l1 denotes a base board. On this base board 11 is fixed by a stop nut 12 (FIG. 2) a bearing cylinder 13. Into the bearing cylinder 13 is inserted a rotary shaft 14 in a manner to penetrate the base board 11. At the upper end is fixed a space pinion l5, and at the lower end of the rotary shaft 14 is disposed an escapement wheel 16 provided with a plurality of teeth like saw teeth. 17 represents a pawl shaft fitted to the underside of the base board 11 in parallel relationship with the rotary shaft 14. On the pawl shaft 17 are fitted the bent parts of the feed pawl 18 and keep pawl 19 in a superposed state. The feed pawl 18 is bent substantially at the center and comprises a vertical section 18b formed substantially at the central part of one half portion 18a thereof almost at right angles thereto (FIG. 4). Further at the end of the vertical section 18b is formed an engagement section 18c which engages with the escapement wheel 16. The opposite half portion is formed as a depressed arm 18d. Between the projection l8e of said feed pawl 18 and a spring holding strip 20 mounted on the base board 11 is stretched a strong draw spring 21. The elastic force of the spring 21 causes the aforesaid half portion 18a of the feed pawl 18 to contact the stopper 22 embedded in the base board 11 thereby to prevent the clockwise rotation (FIG. 1) of the feed pawl 18 and the engagement section to be disengaged from the escapement wheel 16. Substantially at the central part of the half portion 18a is embedded a stopper 18f. The keep pawl 19 is also bent substantially at the center. One half portion 19a (FIG. 6) is disposed substantially parallel with the vertical section 18b of the feed pawl 18 and has an engagement section 19b integrally formed at the end which engages the escapement wheel 16 at a point several pitches apart from the aforementioned engagement section 18c. The opposite half portion of the keep pawl 19 contacts the stopper 18f in superposed relationship with the half portion 18a of the feed pawl 18. Numeral 23 denotes a minor or weak spring stretched between the vertical section 18b of the feed pawl 18 and the half portion 19a of the keep pawl 19. This spring 23 normally pulls the keep pawl 19 so as to permit its clockwise rotation, and also causes the opposite half portion 190 of the keep pawl 19 to contact the stopper 18f, thereby allowing the keep pawl 19 to move jointly with the feed pawl 18. Under such condition, the engagement section 180 of the feed pawl 18 and the engagement section 1% of the keep pawl 19 are maintained at such relationship that when either of them enters the rotation field of the escapement wheel 16, the other is removed therefrom.

Numeral 24 represents an actuator rotatably engaging a shaft 25 mounted on the base board 11 which faces the rotary shaft 14 and pawl shaft 17 so as to define a triangular shape therewith. Said actuator 24 comprises a contact wheel 26 for contacting the depressed arm 18d of the feed pawl 18 to urge it against the elastic force of the draw spring 21, a depressed section 27 positioned between the rotary shaft 14 and the aforesaid pivotal shaft and a long arcuate idle hole 28 bored by the side of the contact wheel 26. Numeral 29 denotes an interlocking member which comprises a pin-like urged member 32 and a push arm 31 laid between the rotary shaft 14 and pivotal shaft 25 both mounted on the base board 11 in a manner to engage a fixed horizontal shaft and contact the depressed section 27 of the actuator 24. In this embodiment, an escapement mechanism comprises the escapement wheel 16, pawl shaft 17, feed pawl 18, keep pawl 19, actuator 24, shaft 25, and escapement plate 37.

Numeral 33 (FIG. 1) denotes a carriage urging member or spring drum in which there is accumulated an urging force when a carriage 34 is moved opposite to the direction indicated by the arrow A of FIG. 1. This urging force normally causes the carriage 34 to move in the letter feed direction, namely, in the direction of the arrow A of FIG. 1 through a connection string 35. On said carriage 34 is mounted a platen 34a. Numeral 36 denotes a rack fitted to the carriage 34. The rack 36 engages the space pinion 15, thereby causing the escapement wheel 16 to rotate clockwise (FIG. 1) due to the travel of the carriage 34 in the letter feed direction. When the rack 36 rotates counterclockwise from the position of FIG. 2 through operation of a release lever 36a (shown in dotted line) mounted on the carriage 34, the rack 36 is disengaged from the space pinion l5. Numeral 37 denotes an escapement plate travelling back and forth in the directions indicated by the arrows B and C in FIG. 3 in conjunction with the reciprocation of a type bar (not shown). The advance of the escapement plate 37 in the direction of the arrow B rotates the actuator 24 through the interlocking member 29 against the elastic force of the draw spring 21. Numeral 38 denotes a space lever, the bent portion of which is fitted to a machine frame (not shown) in a manner to rotate about a shaft 39 (FIG. 1). To one end of the space lever 38 is connected one end of a connection rod 40, the opposite end of which engages the long idle hole 28 perforated in the actuator 24. To the opposite end of the space lever 38 is connected one end of a connection rod 41. The other end of the latter connection rod 41 is rotatably fitted to the projecting portion 42a of a connection rod 42 by a shaft 43. One end of the last mentioned connection rod 42 is fixed to a rotatable member 44 assuming an L-shaped cross section which is rotatably fitted to the machine frame, and the opposite end of said connection rod 42 is fixed to a space bar 45. Thus the reciprocation of the space bar 45 is converted through the connection rod 42 to the reciprocation of the rotatable member 44, which in turn is converted through the connection rod 41 to the rotation of the space lever 38, said rotation being further transmitted through the connection rod 40 to rotate the actuator 24.

Numeral 46 denotes a substantially L-shaped lever, the bent central part of said lever 46 being rotatably fitted to the base board 11 by a shaft 47. At one end of the lever 46 is formed a spring holding strip 460, and between said strip 460 and the half portion 18a of the feed pawl 18 is stretched a draw spring 48. To the opposite end of said feed pawl biasing lever 46 is connected one end of a connection rod 49, the opposite end of which is connected to one end of a bell crank lever 50. The bent central part of the bell crank lever 50 is rotatably fitted to the machine frame by a shaft 51. At the opposite end of said crank lever 50 is formed an engagement groove 50a, which engages one end of a connection rod 52. The opposite end of said connection rod 52 is rotatably fitted to the projecting portion 53a of another connection rod 53 by a shaft 54. One end of the latter connection rod 53 is fixed to a repeat spacing key 55, and the opposite end to a rotatable member 56 assuming an L-shaped cross section and rotatably fitted to the machine frame. When the repeat spacing key is depressed, the resultant moment is converted to the rotation of the rotatable member 56, which in turn is converted through the connection rod 52 to the counterclockwise rotation (as viewed from FIG. 1) of the bell crank lever 50, this counterclockwise rotation being further transmitted through the connection rod 49 to rotate the feed pawl biasing lever 46 clockwise (as viewed from FIG. 1).

There will now be described the operation of this embodiment arranged as described above. When the escapement plate 37 is retracted as shown in FIG. 3, the feed pawl 18 and keep pawl 19 are brought to a position shown in FIG. 1 by the elastic force of the draw springs 21 and 23. The engagement section 18c is disengaged from the escapement wheel 16 while the engagement section 19b engages therewith to arrest the carriage 34. When the escapement plate 37 travels forward in the direction of the arrow B interlockingly with the printing operation of a type bar (not shown), the interlocking member 29 is urged in the forward direction as indicated in FIG. 3 to rotate the actuator 24, so that the contact wheel 26 pushes the depressed arm 18d to rotate the feed pawl 18 against the draw spring 21 and bring the engagement section 18c of the feed pawl 18 into the rotation field of the escapement wheel 16. Under this condition, the half portion of the keep pawl 19 is rocked counter clockwise by the stopper 18fwhich moves together with the feed pawl 18 so that the keep pawl 19 is urged by the stopper 18f to rotate in the same direction as that in which the feed pawl 18 rotates, causing the engagement section 19b to be disengaged from the wheel 16, so that said wheel 16 is allowed to continue rotation until it engages the engagement section 18c to cause the carriage 34 to travel half the tooth pitch in the letter feed direction. Thus will result the condition of FIG. 4. When the type bar is brought back to its original position after printing and in consequence the escapement plate 37 is returned in the direction of the arrow C, then the feed pawl 18 is rotated by the elastic force of the draw spring 21 until it contacts the stopper 22, thereby releasing the engagement section 18c from the escapement wheel 16 and pushing back the actuator 24 by the action of the depressed arm 18d. Further, the keep pawl 19 is rotated by the draw spring 23 in succession to the feed pawl 18 so as to bring the engagement section 19b of the keep pawl 19 into the rotation field of the escapement wheel 16. Accordingly, the toothed wheel 16 is allowed to continue rotation until it engages the engagement section 19b of the keep pawl 19 to cause the carriage 34 to travel half the tooth pitch. Thus the escapement wheel 16 is brought back to the position illustrated in FIG. 1. Each time printing is carried out by the type bar through the aforementioned operation, the feed pawl 18 and keep pawl 19 are alternately engaged with and disengaged from the escapement wheel 16, permitting the carriage 34 to travel one pitch in the letter feed direction during one cycle of this operation.

Where the space bar 45 is used in effecting repeat spacing, there will also be carried out substantially the same operation as described above. Namely, when the space bar 45 is depressed, the space lever 38 is rotated clockwise (as viewed from FIG. 1) through the connection rod 42, rotatable member 44 and the connection rod 41 in turn, thereby rotating the actuator 24 clockwise through the connection rod 40. As in the previous case, therefore, the feed pawl 18 and keep pawl 19 assume the same relationship as illustrated in FIG. 4. When the space bar 45 is brought back to its original position to be released from depression, then there will be performed the reverse operation to that which is conducted when the space bar 45 is depressed. Thus the space lever 38 and actuator 24 together are rocked counterclockwise (as viewed from FIG. 1) and the feed pawl 18 and keep pawl 19 assume the relationship shown in FIG. 1, causing the carriage 34 to travel one tooth pitch.

Next when, under the condition of FIG. 1, there is depressed the repeat spacing key 55, then the bell crank lever 50 is rocked counterclockwise through the connection rod 53, rotatable member 56 and the connection rod 52 in turn, and the feed pawl biasing lever 46 is rocked clockwise through the connection rod 49. Clockwise rocking of said feed pawl biasing lever 46 causes the feed pawl 18 to rock counterclockwise through the draw spring 48 against the draw spring 21, and the engagement section 18c of the feed pawl 18 to be brought into the rotation field of the escapement wheel 16. At this point, the keep pawl 19 is urged by the stopper 18f and rocked counterclockwise about the pawl shaft 17, so as to disengage the engagement section 19b therefrom. Accordingly, the escapement wheel 16 continues rotation until it engages the engagement section 180 to permit the carriage 34 to travel half the tooth pitch in the letter feed direction. Thus will result the condition of FIG. 5. Since, the force of urging the carriage 34 in the letter feed direction is exerted on the tooth wheel 16 through the rack 36 and space pinion so as to rotate the toothed wheel 16 clockwise, a cam action takes place under the conditions of FIG. 5, between the toothed wheel 16 and the engagement section 180 of the feed pawl against the bias of the draw spring 48, thereby effecting clockwise rotation of the feed pawl 18 so as to cause the engagement section 18c to be disengaged from the toothed wheel 16. At this time, the keep pawl 19 is rocked by the draw spring 23 in succession to the feed pawl 18 to bring the engagement section 19b of the keep pawl 19 into the rotation field of the escapement wheel 16. Accordingly, the escapement wheel 16 is allowed to continue rotation until it engages the engagement section 19b of the keep pawl 19, thereby permitting the carriage 34 to travel half the tooth pitch in the letter feed direction. Thus will be presented the condition of FIG. 6. Since the repeat spacing key 55 is held depressed even under this condition, the feed pawl biasing lever 46 is still in the clockwise rotated position, causing the feed pawl 18 to rock against the draw spring 21, so that said feed pawl 18 is again rocked against said draw spring 21, resulting in the condition of FIG. 5. Repetition of the same operation as described above will allow the feed pawl 18 and keep pawl 19 to be repeatedly engaged with and disengaged from the escapement wheel 16 in alternate relationship due to the elastic force of the draw spring 48 and the cam action exerted by the engagement section of the feed pawl 18 jointly with the teeth of the wheel 16. Thus while the repeat spacing key 55 is depressed, the carriage 34 performs a repeat spacing movement at a prescribed speed automatically and continuously.

Upon release of the repeat spacing key 55, there will be carried out a reverse operation to the case of its depression. Namely, the feed pawl biasing lever 46 is rocked counterclockwise and brought back to the position of FIG. 1 so that the draw spring 48 may cease to apply the biasing force which effects counter clockwise rotation of the feed pawl 18 against the bias of the draw spring 21, thereby stopping the repeat spacing movement of the carriage 34.

When, in the above case, the type bar or space bar 45 is depressed to rock the actuator 24 and in consequence cause the engagement section 18c of the feed pawl 18 to engage the escapement wheel 16, then there tends to occur a cam action exerted by the teeth of the wheel 16 jointly with the engagement section 180. However, while the type bar or space bar 45 is depressed, the contact wheel 26 of the actuator 24 contacts the depressed arm 18d of the feed pawl 18 to obstruct the aforesaid cam action, and so the engagement section 18c will remain engaged with the escapement wheel 16 until the actuator 24 is brought back to its original position. In this respect, depression of the repeat spacing key 55 has the advantage of effectively utilizing the cam action, because said depression does not put the actuator 24 into operation. For instance, if the repeat spacing key 55 is actuated by mistake when the type bar or space bar 45 is depressed, said depression puts the actuator 24 into operation to restrict the aforesaid cam action, offering the advantage of preventing the unnecessary repeat spacing movement of the carriage 34 arising from an erroneous operation.

As mentioned above, the foregoing embodiment enables the carriage 34 reliably to carry out a repeat spacing movement and moreover causes the escapement wheel 16, feed pawl 18, keep pawl 19 and feed pawl biasing lever 46 to be mounted on the base board 11 in a manner to rotate in a plane parallel therewith, permitting the flat compact formation of the entire mechanism, so that this embodiment is fully adapted for use in a typewriter like a portable type which is desired to be as much reduced in size and weight as possible.

FIG. 7 represents another embodiment of the present invention. The same parts of this figure as those of FIG. 1 are denoted by the same numerals and description thereof is omitted. FIG. 7 differs from FIG. 1 in that one half portion 18a of the feed pawl 18 is fitted at the end with an inertia increasing member or a weight 57. If, in case there is not provided an inertia increasing member 57 as in FIG. 7, the weight of the feed pawl 18 and the elastic force of the draw spring 48 are not properly selected, then the engagement or disengagement of the engagement section 18c of the feed pawl 18 with respect to the escapement wheel 16 will be conducted at a far greater speed than otherwise, likely leading to an unduly rapid repeat spacing movement of the carriage 34, so that when the repeat spacing key 55 is relieved of depression, the carriage 34 will undesirably overrun the prescribed stop position. Accordingly, attachment of an inertia increasing member 57, for example, to the end of one half portion 180 of the feed pawl 18 will retard the response speed of the feed pawl 18 to the cam action exerted by the engagement section 180 jointly with the teeth of the wheel 16, causing the carriage 34 to perform a repeat spacing movement at a proper speed exactly equal to one letter space each time. There is the further advantage that where the repeat spacing key 55 is actuated, the carriage 34 is unfailingly prevented from travelling beyond its desired stop position.

FIG. 8 denotes still another embodiment of the present invention. The same parts as those of FIG. 7 are indicated by the same numerals and description thereof is omitted. The embodiment of FIG. 8 differs from FIG. 7 in the following respect. The spring holding strip 46a formed at one end of the feed pawl biasing lever 46 is omitted and instead there is provided a spring holding member 58 comprising a long hole 58a extending lengthwise of the central part and a spring holding strip 58b disposed at one end. This spring holding member 58 is fitted to one end of the feed pawl biasing lever 46' by a screw 59 inserted into the long hole 58a. And between the spring holding strip 581; and the end of the half portion 18a of the feed pawl 18 is stretched the draw spring 48. Adjustment of the fitting position of the spring holding member 58 by loosening the screw 59 permits the control of the elastic force of the draw spring 48 acting on the feed pawl 18. Such control of the elastic force of the draw spring 48 acting on the feed pawl 18 varies its response speed to the cam action exerted by the engagement section 18c jointly with the escapement wheel 16, enabling the carriage 34 to carry out a repeat spacing movement at a desired speed.

According to the embodiment of FIG. 8, the feed pawl urging lever 46 of FIG. 7 was fitted with the spring holding member 58. However, attachment of said member 58 to the similar lever 46 of FIG. 1 will display the same effect.

It will be apparent that the present invention is not limited to the embodiments described by reference to the appended drawing, but may be applicable to other modifications without changing the object and scope of the invention.

What is claimed is:

1. A repeat spacing mechanism for typewriters comprising,

a. a base board,

b. a platen supporting carriage on said base board and movable both in a letter feed direction and in the opposite direction;

0. means for urging said carriage in the letter feed direction,

d. an escapement mechanism for an incremental spacing movement of said carriage in the letter feed direction upon typing operation, said escapement mechanism comprising,

a wheel shaft vertically and pivotally mounted on the base board,

a toothed wheel secured to said shaft and operatively connected to said carriage,

a pawl shaft mounted on said base board in spaced parallel relation to said wheel shaft,

a feed pawl and a keep pawl registerable with said toothed wheel and rockably mounted on said pawl shaft in a plane parallel with said wheel,

connecting means for connecting said feed pawl with said keep pawl as a unit so as to alternately engage said wheel, and a first spring connected to said feed pawl for biasing said feed and keep pawls so as to rotate both of said pawls in a first direction in which said feed pawl is normally disengaged from said wheel and said keep pawl is normally engaged with said wheel,

e. a depressible repeat spacing key,

f. a lever pivotally mounted on said base board and connected with said repeat spacing key to rock in a plane parallel to the rotation plane of said wheel upon depression of said repeat spacing key,

g. a second spring directly connected to said feed pawl and said lever and stretched therebetween to bias said feed and keep pawls thereby to rock said feed and keep pawls in a second direction in which said feed pawl is engaged with said wheel and said keep pawl is disengaged therefrom upon depression of said repeat spacing key,

h. an engagement section formed on said feed pawl and engageable with said wheel to cause a cam action to be exerted between said engagement section and said wheel so as to rotate said feed and keep pawls in said first direction during depression of said repeat spacing key, whereby said feed pawl and said keep pawl are alternately and cyclically engaged with and disengaged from said wheel to rotate said wheel so as to cause said carriage to make a repeat spacing movement in the letter feed direction while said repeat spacing key is held depressed. 

1. A repeat spacing mechanism for typewriters comprising, a. a base board, b. a platen supporting carriage on said base board and movable both in a letter feed direction and in the opposite direction; c. means for urging said carriage in the letter feed direction, d. an escapement mechanism for an incremental spacing movement of said carriage in the letter feed direction upon typing operation, said escapement mechanism comprising, a wheel shaft vertically and pivotally mounted on the base board, a toothed wheel secured to said shaft and operatively connected to said carriage, a pawl shaft mounted on said base board in spaced parallel relation to said wheel shaft, a feed pawl and a keep pawl registerable with said toothed wheel and rockably mounted on said pawl shaft in a plane parallel with said wheel, connecting means for connecting said feed pawl with said keep pawl as a unit so as to alternately engage said wheel, and a first spring connected to said feed pawl for biasing said feed and keep pawls so as to rotate both of said pawls in a first direction in which said feed pawl is normally disengaged from said wheel and said keep pawl is normally engaged with said wheel, e. a depressible repeat spacing key, f. a lever pivotally mounted on said base board and connected with said repeat spacing key to rock in a plane parallel to the rotation plane of said wheel upon depression of said repeat spacing key, g. a second spring directly connected to said feed pawl and said lever and stretched therebetween to bias said feed and keep pawls thereby to rock said feed and keep pawls in a second direction in which said feed pawl is engaged with said wheel and said keep pawl is disengaged therefrom upon depression of said repeat spacing key, h. an engagement section formed on said feed pawl and engageable with said wheel to cause a cam action to be exerted between said engagement section and said wheel so as to rotate said feed and keep pawls in said first direction during depression of said repeat spacing key, whereby said feed pawl and said keep pawl are alternately and cyclically engaged with and disengaged from said wheel to rotate said wheel so as to cause said carriage to make a repeat spacing movement in the letter feed direction while said repeat spacing key is held depressed. 